Liquid silicone is one type of silicon polymer that is frequently used to create molds for various industrial products. It is most commonly used in molds for rubber, resin, foam, and metals that have a low melting point. Household items, such as rubber spatulas, baking dishes, and baby bottle nipples, are also made from this material. Generally, liquid silicone is favored over other materials for these applications because of its flexibility, viscosity, strength, versatility, and lower costs.
Most silicone rubbers have a high tolerance for heat, fire, and cold. This makes them ideal molds for certain metal alloys, as they will be able to hold metals that melt at reasonably low temperatures. The cost of liquid silicone molds is generally lower than the ceramic molds typically used for metals. Liquid silicone is also chemically inert, which makes it a good candidate for products that come into contact with food, or for molds that come into contact with more reactive compounds. It is also water resistant due to its chemical structure, which includes hydrophobic, or water-fearing, methyl groups.
The qualities of liquid silicone can be tailored to the specific needs of the manufacturer because it is an adjustable silicone mixture. For instance, the chemicals added to the silicone mixture could either strengthen it as an electrical insulator, or could change it into a conductor. The color, opacity, firmness, and texture of the liquid silicone can also be adjusted, making it a practical choice for a wide range of household products.
Liquid silicone is usually fashioned into molds or products through a process known as liquid injection molding. During this process, the silicone rubber is loaded into a plunger and pumped into a mixer, along with a catalyst and any coloring materials or other chemical additions. A device called the metering unit allows the mixing reaction to be carefully controlled, as it maintains a slow release of the silicone and the catalyst in accurate quantities. The catalyst, which typically contains platinum, activates the silicone, causing it to harden once the mixture is pumped into the mold. After that the mold is sealed closed with a mold clamp until the silicone is set, and then it is removed and the silicone product is almost complete.
The liquid injection molding technique allows for more thorough and uniform mixing of the silicone in its liquid form. This makes the finished silicone products to be chemically and structurally consistent throughout, and it also means that separate products that have the same mixing formula will be more consistent with each other when manufactured in this way. The process also allows for faster setting times for the liquid silicone rubber.